Servo motor transfer function, how to get it with?

I bought a pan and tilt kit from lynxmotion, I’m going to use it for color tracking so the pan and tilt is going to have a web camera attached to it.

This is going to be an automatic control system, so I need to get the transfer function from each servo(pan and tilt separatetly), as a servo is a controlled system itself, I consider it a system with no error; this means, I assume it goes exactly to the position I “tell” it to go; so the only variable to consider here is the time it takes it to the servo to go that position, this means I need to get the transfer function for the servos in terms of the time(delay) to position.

My pan and tilt is this one lynxmotion.com/p-287-lynx-b- … dized.aspx. I know the manufacturer specifies this
Speed (4.8V/6.0V): 0.21 / 0.16 sec @ 60 deg.

BUT this specification is for a motor with no load at all. The tilt servo is going to have the camera as load, and the pan servo is going to have the tilt and the camera as load so this is going to affect the dynamics of the the servos.

My idea is to measure the voltage related to a position and measure the time it takes to get to that voltage.

any suggestion on how to do it?

thanks
Carlos

Some info below on reading the voltage/position from the pot in a servo:

viewtopic.php?f=2&t=2748
viewtopic.php?f=31&t=3182

The part you are missing is you do not have to move at the top speed. Servo controllers are wonderful at providing the necessary pulses to slow the movements down. At top speed the motion is not controlled well. You must slow the movement down for the best results.